[action] [PR:3910] Improved GCU's field validation logic for the WRED_PROFILE table

[mssonicbld]

What I did

When using config apply-patch to update CONFIG_DB, GCU tries to validate the patch according to the rules in gcu_field_operation_validators.conf.json. As explained in Issue 22295, since fields for the WRED_PROFILE table in this file contain the profile name azure_lossless, patches that target other WRED profiles will be rejected with the following error:

Error: Failed to apply patch on the following scopes:
- localhost: Modification of WRED_PROFILE table is illegal- validating function generic_config_updater.field_operation_validators.rdma_config_update_validator returned False

How I did it

1. Modified gcu_field_operation_validators.conf.json to remove the profile name azure_lossless from WRED_PROFILE fields.
2. In order to minimize side effect for other tables, we created a new validation function specifically for the WRED_PROFILE table named wred_profile_config_update_validator. This function modifies the path in patch by removing the table name (i.e., WRED_PROFILE), and then converting the whole path to lowercase. Then it verifies that the last part of this path matches a field defined in gcu_field_operation_validators.conf.json for the WRED_PROFILE table. For example, a path like /WRED_PROFILE/AZURE_LOSSY/green_min_threshold will be converted to azure_lossy/green_min_threshold, which will match green_min_threshold.

How to verify it

Store a JSON patch that targets a WRED profile different from azure_lossless in a file, and then run sudo config apply-patch {your_patch_name.json}.

Test 1: Wrong WRED profile name
Patch: [{"op": "replace", "path": "/WRED_PROFILE/DUMMY/green_min_threshold", "value": "1234"}]
Result:

Failed to apply patch due to: Validate json patch: [{"op": "replace", "path": "/WRED_PROFILE/DUMMY/green_min_threshold", "value": "1234"}] failed due to:member 'DUMMY' not found

Test 2: Existing field name that is not in gcu_field_operation_validators.conf.json
Patch: [{"op": "replace", "path": "/WRED_PROFILE/AZURE_LOSSY/red_min_threshold", "value": "1234"}]
Result:

Error: Failed to apply patch on the following scopes:
- localhost: Modification of WRED_PROFILE table is illegal- validating function generic_config_updater.field_operation_validators.wred_profile_config_update_validator returned False

Test 3: Correct patch for 1 field
Patch: [{"op": "replace", "path": "/WRED_PROFILE/AZURE_LOSSY/green_min_threshold", "value": "1234"}]
Result:

Patch applied successfully.
$ ecnconfig -l
Profile: AZURE_LOSSY
-----------------------  -------
...
green_min_threshold      1234
...
-----------------------  -------

Test 4: Non-existent field name
Patch: [{"op": "replace", "path": "/WRED_PROFILE/AZURE_LOSSY/min_threshold", "value": "2468"}]
Result:

Error: Validate json patch: [{"op": "replace", "path": "/WRED_PROFILE/AZURE_LOSSY/min_threshold", "value": "2468"}] failed due to:can't replace a non-existent object 'min_threshold'

Test 5: Correct patch for multiple fields
Patch: [{"op": "replace", "path": "/WRED_PROFILE/AZURE_LOSSY/green_min_threshold", "value": "2468"},{"op": "replace", "path": "/WRED_PROFILE/AZURE_LOSSY/green_max_threshold", "value": "9876"},{"op": "replace", "path": "/WRED_PROFILE/AZURE_LOSSY/green_drop_probability", "value": "10"}]
Result:

Patch applied successfully.
$ ecnconfig -l
Profile: AZURE_LOSSY
-----------------------  -------
...
green_drop_probability   10
green_max_threshold      9876
green_min_threshold      2468
...
-----------------------  -------

Previous command output (if the output of a command-line utility has changed)

N/A

New command output (if the output of a command-line utility has changed)

N/A

[mssonicbld]

Original PR: #3910

[mssonicbld]

/azp run

[azure-pipelines]

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